In the co-current gas-liquid upflow reactors, liquid is the continuous phase and gas dispersed phase. It is critical to distribute gas uniformly across the reactor cross section, which is achieved by building a gas chamber under a distribution tray so that gas can be distributed through restriction orifices on distributors located across the distribution tray. Good tray performance requires there to be a stable gas-liquid interface below the tray. When the gas-liquid feed stream is injected into the bottom of reactor, gas bubbles travel upwards and disrupt the gas-liquid interface, which negatively impacts gas distribution in the tray.